Successful gene therapy for the respiratory manifestations of cystic fibrosis (CF) requires efficient transfer of the normal cystic fibrosis transmembrane conductance regulator (CFTR) cDNA to the airway epithelium in sufficient amount, distribution and persistence to correct the deficiency of CFTR function that characterizes the airway abnormalities in this disorder. Replication deficient, recombinant adenovirus (Ad) vectors based on group C Ad backbones have many advantages as gene transfer vectors to achieve this goal, but the vectors in their present form are not capable of providing persistent, high level correction of the deficiency of CFTR function in the airway epithelium. Based on the concept that the interaction of Ad vectors with the epithelium and many of the host responses to Ad vectors are dependent on specific epitopes in the Ad capsid (fiber, penton base, and/or hexon), this project is focused on understanding the biologic processes related to the unidirectional trafficking from cell surface to nucleus demonstrated by Ad vectors with modified capsid components interacting with airway epithelial cells. The underlying thesis of this project is that an understanding of how the Ad translocates within the cell, and how Ad serotypes and chimeric Ad vectors differ in this process, will help in designing gene transfer vectors that can reach the target cell nucleus of differentiated airway epithelium with maximum efficiency. The crux of the studies will be to evaluate the intracellular biologic processes associated with translocation of the Ad vector prior to the time the Ad vector genome is transcribed by the target cell. This project has three specific aims: (1) To examine the hypothesis that the kinetics of the Ad binding, entry, intracellular translocation, nuclear binding and/or the fate of the capsid can be modified by altering individual components of the Ad capsid; (2) To evaluate the hypothesis that Ad virions are actively transported to the nucleus along cytoskeleton elements; and (3) To assess the hypothesis that the Ad capsomere contains nuclear envelope targeting information.